Fuel supply device for an internal combustion engine

ABSTRACT

In providing a separate supply of fuel to an internal combustion engine when it is started up from a cold condition or as it idles following a cold start up, an additional supply of fuel is withdrawn from the engine carburetor float chamber and is passed through a valve operated fuel well into a fuel chamber. The fuel well is opened when the intake manifold of the engine is at atmospheric pressure for passing fuel into the fuel chamber. A fuel line connects the fuel chamber to the venturi tube for supplying fuel to the engine and a branch pipe, communicating with the fuel line, adds air to the fuel as it is directed into the venturi tube. The passage of fuel through the fuel line is discontinued in response to a temperature sensing arrangement which checks the engine temperature and, when a predetermined temperature level is reached, cuts off the flow through the fuel line to the venturi tube.

States atet [191 Matsumoto et a1.

[ 1 Mar. 25, 1975 1 1 FUEL SUPPLY DEVICE FOR AN INTERNAL COMBUSTIONENG1NE [75] Inventors: l-lirofumi Matsumoto; Masahiko Nakada, both ofToyota, Aichi-ken, ap n .1 .s .1

[73] Assignee: Toyota Jidosha Kogyo Kahushilti Kaisha, Toyota,Aichi;ken,1apan [22] Filed: May 30, 1973 [21] Appl. No.: 365,057

[30] Foreign Application Priority Data July 19, 1972 Japan 47-71631 [52]U.S. Cl 123/180 R, 123/187.5 R, 261/39 D [51] Int. Cl. F02m 1/08 [58]Field of Search..... 123/179 6,179 A, 187.5 R,

123/180 R; 261/D1G. 8, 39 D United Kingdom 123/ 179 G PrimaryExaminer-Charles J. Myhre Assistant Examiner-W1 Rutledge, Jr.

Attorney, Agent, or Firm-Toren. McGeady and Stanger [57] ABSTRACT Inproviding a separate supply of fuel to an internal combustion enginewhen it is started up from a cold condition or as it idles following acold start up, an additional supply of fuel is withdrawn from the enginecarburetor float chamber and is passed through a valve operated fuelwell into a fuel chamber. The fuel well is opened when the intakemanifold of the engine is at atmospheric pressure for passing fuel intothe fuel chamber. A fuel line connects the fuel chamber to theventuritube for supplying fuel to the engine and a branch pipe,communicating with the fuel line, adds air to the fuel as it is directedinto the venturi tube. The passage of fuel through the fuel line isdiscontinued in response to a temperature sensing arrangement whichchecks the engine temperature and, when a predetermined temperaturelevel is reached, cuts off the flow through the fuel line to the venturitube.

6 C1aims, 2 Drawing Figures mEmmmzsmrs sum 1 OF 2 FIG;

FUEL SUPPLY DEVICE FOR AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention is directed toa device for reducing the amount of exhaust gases generated during thecold start up and idling following cold start up of an internalcombustion engine equipped with an automatic choking mechanism.

2. Description of the Prior Art.

When an internal combustion engine is warming up, the rich air-fuelmixture supplied by the automatic choke gives off exhaust gases whichhave a greater carbon monoxide and hydrocarbon content than in theemissions from the engine when it is running at normal operatingtemperature. To reduce the proportions of such noxious components'fromthe exhaust, the automatic choking effect must be lessened and thechoking time shortened. However, a lean mixture results and tends tocause difficulty in cold start up and to make idling unstable. Further,the use of a lean mixture may even increasethe volume of harmful exhaustemissions.

SUMMARY OF THE INVENTION Therefore, it is the primary object of thepresent invention, to eliminate the disadvantages experienced in thepast by providing a device which provides a separate additional supplyof fuel to the engine during cold start up and idling so that the enginehas the same operating stability as when full use of the choke is made.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated and described preferredembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a schematic side view, partly in section, of one embodiment ofthe present invention; and

FIG. 2 is a schematic side view, similar to FIG. 1, of anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION For the sake of simplicity andclarity only the essential portions of the engine incorporating thepresent invention are shown in the drawings.

In FIG. 1, a carburetor l is arranged to supply fuel from a fuel chamberand to inject it by the well-known action of a venturi, not shown, intoa venturi tube 3 with the resulting air-fuel .mixture being admitted,under the flow control of a throttle valve 4, into an internalcombustion engine, not shown, via an intake manifold 5.

Between the float chamber 2 of the carburetor and the portion of theventuri tube 3 downstream of the throttle valve 4, an arrangement isprovided for supplying additional fuel into the venturi tube during coldstart up and idling of the engine. The arrangement consists ofa devicefor withdrawing fuel from the float chamber in dependence on thenegative pressure or depression in the manifold, a conduit arrangement30 for conveying fuel from the device 10 into the venturi tube by meansof the suction action provided by the engine, and a device 40 forcutting off flow ofthetfuel through the conduit arrangement 30 when theoperating temperature of the engine has risen to a pre-determined level.

The device 10 includes a fuel well 13 in communication with the floatchamber 2 through a fuel intake pipe 11 and an air pipe 12. Within thefuel well 13, apiston 16 is displaceably positionable for regulatingflow from the fuel well. A spring 14 biases the piston while a stopper15, located above the inlet of the air pipe 12 into the fuel well,limits the downward movement of the p'iston. The piston 16 forms anupper space which is in communication with the intake manifold 5 througha manifold line 17. Adjacent its lower end, the fuel 'well has a valveseat 18 and a valve 20 is arranged for nor mally closing the valve seatand preventing flow out of the fuel well. A spring 19, having a weakerspring characteristic than the spring 14 acting on the piston, normallymaintains the valve in the closed position. The lower end of the piston16 contacts the upper end of the valve 20 for opening the valve ,whenthe piston is displaced downwardly. The lower end of the fuel well 13,normally closed by the valve 20, communicates through a fuel passage 21with a fuel chamber 22. Flow from the fuel well enters the fuel chamberthrough its lower end. An orifice 23 is located at the opening into thelower end of the fuel chamber 22 and a check ball 24, shown floating onthe level of the fuel in FIG. 1, seats in the orifice 23 when the fuelchamber is empty forming a closure for the opening from the lower end ofthe chamber.

When the intake manifold 5 is at atmospheric pressure, this pressurecondition is conveyed through the line 17 into the fuel well above thepiston 16 and, in combination with the spring, urges the pistondownwardly'and opens the valve 20 against the action of the spring 19.With the valve 20 open fuel flows downwardly out of the fuel Wellthrough-the passage 21 into the fuel chamber 22. On the other hand, if avacuum exists within the intake chamber, the vacuum acts on the piston16 within the upper end of the fuel well so that the piston ismovedupwardly and the valve 20, under the biasing action of the spring,closes the valve seat and cuts off the flow of fuel into the fuelchamber 22.

The conduit arrangement 30 consists of a nozzle 31 connected to theportion of the venturi tube 3 downstream of the throttle valve, a supplypassage 32 extending through the housing forming the fuel chamber fromthe lower end of the chamber to a point above the fuel level in thechamber and then changes direction and flows downwardly through thehousing to a lower point where it is connected to a supply line 33 whichis connected at its opposite end to the nozzle 31. Communicating withthe upper part of the supply passage 32 is a passage 34 which suppliesatmospheric air into .the supply passage and also supplies the air intothe upper end of the fuel chamber. Due to the suction or drawing actionof the engine, as it operates, the fuel is withdrawn from the fuelchamber through the fuel passage 32 where air, from the passage 34, ismixed with it so that the mixture then flows through the line 33 and thenozzle 31 into the venturi tube 3. When the fuel chamber has beenemptied, the check ball 24 seats within the orifice 23 and closes theopening to the supply passage 32 and cuts off the flow of excess air.

The device 40 is made up of a casing 41 secured with its bottom incontact with the intake manifold 5 and an opening is provided in thecasing which communicates its interior with the ambient atmosphere.Within the casing a valve 44 is supported on the end of an elongatedbimetal member 42 which bends in response to the engine temperaturewithin the intake manifold. The valve 44 is arranged to open or close ahole 43 in the casing and an air line 45 communicates between the hole43 and the supply passage 32 at a point downstream from the point atwhich the branch passage 34 communicates with the supply passage. Whenthe operating temperature of the engine is low, the bimetal member 42positions the valve so that it closes the hole 43. As the operatingtemperature of the engine increases, the bimetal member 42 is graduallyheated and assumes a bent configuration withdrawing the valve 44 fromthe hole 43 so that atmospheric air within the casing 41 flows throughthe air line 45 into the supply passage 32 and increases the pressure inthe supply passage to an extent so that fuel is no longer withdrawn fromthe fuel chamber 22.

In view of the arrangement and function of the elements described above,fuel is supplied to the engine at cold start up and idling in thefollowing manner. With the engine stopped and in a cold condition, andwith the intake manifold at atmospheric pressure, the valve is openedand allows fuel from the float chamber 2 of the carburetor to flowthrough the fuel well 13 into the fuel chamber 22 up to the same fuelheight or level as in the float chamber 2. With the engine at atemperature below the predetermined level, the device 40 maintains thevalve 44 closed across the hole 43 so that seat 18 and discontinues flowof the fuel into the fuel chamber 22. In addition, the negative pressureconditions also act on the venturi tube 3 as well as on the fuel supplysystem. Consequently, additional fuel is continuously supplied to theengine through the conduit arrangement 30 until the fuel in the fuelchamber 22 is exhausted or the engine has warmed up to an extent thatthe predetermined level has been reached at which the bimetal member 42displaces the valve 44 from the hole 43 in the casing 41. If the enginehas already been warmed up, at start up the device prevents anyadditional flow of fuel from the fuel chamber 22 into the venturi tube3. If the engine stalls because all of the fuel has been emptied fromthe fuel chamber 22 due to a comparatively extended warming-up period,the fuel chamber is replenished with fuel immediately after the enginestops. The fuel supply passage 32 and the air passage 34 are providedwith orifices 35, and the duration and amount of fuel supply can be set,as desired, by modifying the diameter of the orifices and the capacityof the fuel chamber.

In FIG. 2 another embodiment of the invention is illustrated in whichthe valve mechanism of the device 10 and the temperature-sensingmechanism of the device 40 are modified. In the device of FIG. 2, avalve port 25 is located at the lower end of the fuel well incommunication with the fuel passage 21. In the upper end ofthe fuelwell, a diaphragm 27 forms a diaphragm chamber 28 above the level of thefuel in the well and a valve stem of a valve 26 which opens and closesthe valve port 25 is secured to the diaphragm. Fuel for the floatchamber 2 is withdrawn from a fuel tank 6 by a fuel pump 7 and isconveyed into the float chamber through a line 8. A branch connection inthe line 8 extends into the diaphragm chamber 28 in the upper end of thefuel well. Thus, while the engine is running, the pressure in the line 8acting within the diaphragm chamber 28 biases the valve 26 downwardlyand closes the valve port so that flow of fuel to the fuel chamber 22 iscut off. If the pump is not operating the valve 26 is biased upwardlyand fuel can flow through the passage 21 into the fuel chamber.

In FIG. 2, the device 40 includes a temperature sensor 46 arranged todetect the cooling water temperature within a water jacket 9 about theintake manifold 5. A solenoid valve is connected to the air line forregulating flow of atmospheric air into the air line. An electroniccontroller 48is connected to the temperature sensor 46 and to thesolenoid valve. When the temperature of the cooling water in the jacket9 is below a predetermined level the solenoid valve 47 closes off theline 45 and permits passage of the fuel from the fuel chamber into theventuri tube. However, when the cooling water has warmed up to apredetermined value, the temperature sensor signals the electroniccontroller which, in turn, directs a flow of current to the solenoidvalve for positioning it in the open condition for admitting atmosphericair into the line 45. With these two differences in the embodiment ofFIG. 2 as compared to that in FIG. 1, the remaining operation of thearrangement is the same as that described for the arrangement in FIG. 1.The devices 10 and 40 in the two embodiments may be interchanged toprovide a suitable combination.

As described above, the fuel supply system in accordance with thepresent invention, operates so that an extra or additional supply offuel is accumulated while the engine is stopped, and only when theengine is started up and idling under cold conditions, the additionalfuel is supplied together with air to the engine by the suction actionin the venturi tube produced by the engine start up. The supply of theadditional fuel is controlled in accordance with the temperatureconditions of the engine, that is, either the temperature within theintake manifold or of the cooling water within the water jacketcontacting the intake manifold. With the additional fuel supplied, theengine can run under stable conditions during warming up with littleneed for automatic choking. Additionally, it enables the engine to emitcleaner exhaust gases during the warming up period than has been thecase in the past. Further, the embodiment illustrated in FIG. 2 candetermine more precisely the engine conditions during warm up and, as aresult, more accurately control the supply of the addi' tional fuel thanis possible with the embodiment shown in FIG. 1.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. In an internal-combustion engine comprising a carburetor including afloat chamber arranged to contain a supply of fuel, a venturi tubearranged to receive fuel from said float chamber, and an intake manifoldarranged to convey the fuel from the venturi tube into the engine,wherein the improvement comprises first means for providing anadditional fuel supply for cold start up and idling of the engine, saidfirst means comprises a fuel well connected to said float chamber, afuel chamber, a conduit connecting said fuel well to said fuel chamberfor supplying fuel into said fuel chamber from said fuel well, a valvemeans for closing off flow from said fuel well through said conduit intosaid fuel chamber, and pressure means connected to said fuel well foracting on said valve means for opening flow between said fuel well andsaid fuel chamber when the engine is not operating and for closing flowbetween said fuel well and said fuel chamber when the engine isoperating so that when the engine is inoperative a supply of fuel can bestored in said fuel chamber, second means for conveying fuel from saidfuel chamber into said venturi tube, said second means comprising a fuelline connecting said fuel chamber and said venturi tube, and a branchpipe connected to said fuel line and said fuel chamber for introducingatmospheric air into said fuel line, and third means for sensing thetemperature of the engine and being connected to said fuel line fordiscontinuing the flow of fuel therethrough from said fuel chamber tosaid venturi tube when the temperature of the engine reaches apredetermined level.

2. In an internal-combustion engine, as set forth in claim 1, whereinsaid fuel well has a valve port opening from its lower end into saidconduit, said valve means arranged to open and close said valve port,said valve means comprises a valve located in said fuel well fornormally maintaining said outlet closed, a piston arranged within saidfuel well, and said pressure means comprising a passage connecting saidfuel well to said intake manifold so that the pressure within saidintake manifold acts on said piston for opening said valve port whensaid intake manifold is at atmospheric conditions and for closing saidvalve port when said intake manifold is at negative pressure conditions.

3. In an internal-combustion engine, as set forth in claim 1, whereinsaid third means comprises a casing in surface contact with said intakemanifold, the interior of said casing being in communication with theatmosphere, a pipe line connecting said casing to said fuel line andsaid pipe line communicating with said fuel line at a locationdownstream from the connection of said branch pipe to said fuel line, abimetal member positioned within said casing, a valve mounted on saidbimetal member and arranged to maintain the opening closed when theengine temperature is below a predetermined level and to displace thevalve from the opening when the engine temperature reaches apredetermined level for admitting air into said fuel line fordiscontinuing flow therethrough to said venturi tube.

4. In an internal-combustion engine, as set forth in claim 1, whereinsaid fuel well has an outlet from its lower end connected to saidconduit, said valve means arranged to open and close said outlet, saidvalve means comprises a valve member including a valve stem extendingupwardly from said valve member, a diaphragm extending across the upperend of said fuel well and dividing it into a lower fuel containing partand an upper diaphragm chamber, and said pressure means comprises a fueltank, a pipe connecting said fuel tank to said float chamber, a pump forsupplying fuel from said fuel tank to said fuel chamber, and a branchline from said pipe connected to said diaphragm chamber downstream fromsaid pump so that the pressure in said pipe is supplied into saiddiaphragm chamber and when said pump is operating the pressure suppliedinto said diaphragm chamber depresses the valve downwardly into positionfor closing the outlet from said fuel well.

5. In an internal-combustion engine, as set forth in claim 1, wherein awaterjacket is provided about a portion of said manifold intake, saidthird means comprises a temperature sensor arranged to detect the watertemperature within said water jacket, solenoid valve having an openingto the atmosphere, pipe line connecting said solenoid valve to said fuelline and said pipe line communicating with said fuel line at a locationdownstream from the connection of said branch pipe to said fuel line,said solenoid valve arranged to control flow into said pipe line, and anelectronic controller connected to said temperature sensor and saidsolenoid valve so that said temperature sensor signals said electroniccontroller when the temperature of the water in the water jacket reachesa predetermined level and actuates said solenoid valve for admitting theflow of atmospheric air into said pipe line.

6. In an internal-combustion engine, as set forth in claim 1, wherein afuel intake pipe extends between said float chamber and said fuel welland an air pipe located above said fuel intake pipe'extends between saidfloat chamber and said fuel well, said fuel chamber having an opening inits lower end, said conduit connecting said fuel well to said fuelchamber is connected to the lower end of said fuel well and to theopening in the lower end of said fuel chamber, a floatable check balllocated within said fuel chamber for closing off the opening to saidconduit into said fuel chamber when fuel is emptied from said fuelchamber, said fuel line extending upwardly from said fuel chamber to itspoint of connection to said branch pipe and downwardly to said venturitube, a first orifice located in said fuel line at the opening from saidfuel chamber, and second oriflees located in said fuel line and in saidbranch pipe connected to said fuel line for regulating flow of air and

1. In an internal-combustion engine comprising a carburetor including afloat chamber arranged to contain a supply of fuel, a venturi tubearranged to receive fuel from said float chamber, and an intake manifoldarranged to convey the fuel from the venturi tube into the engine,wherein the improvement comprises first means for providing anadditional fuel supply for cold start up and idling of the engine, saidfirst means comprises a fuel well connected to said float chamber, afuel chamber, a conduit connecting said fuel well to said fuel chamberfor supplying fuel into said fuel chamber from said fuel well, a valvemeans for closing off flow from said fuel well through said conduit intosaid fuel chamber, and pressure means connected to said fuel well foracting on said valve means for opening flow between said fuel well andsaid fuel chamber when the engine is not operating and for closing flowbetween said fuel well and said fuel chamber when the engine isoperating so that when the engine is inoperative a supply of fuel can bestored in said fuel chamber, second means for conveying fuel from saidfuel chamber into said venturi tube, said second means comprising a fuelline connecting said fuel chamber and said venturi tube, and a branchpipe connected to said fuel line and said fuel chamber for introducingatmospheric air into said fuel line, and third means for sensing thetemperature of the engine and being connected to said fuel line fordiscontinuing the flow of fuel therethrough from said fuel chamber tosaid venturi tube when the temperature of the engine reaches apredetermined level.
 2. In an internal-combustion engine, as set forthin claim 1, wherein said fuel well has a valve port opening from itslower end into said conduit, said valve means arranged to open and closesaid valve port, said valve means comprises a valve located in said fuelwell for normally maintaining said outlet closed, a piston arrangedwithin said fuel well, and said pressure means comprising a passageconnecting said fuel well to said intake manifold so that the pressurewithin said intake manifold acts on said piston for opening said valveport when said intake manifold is at atmospheric conditions and forclosing said valve port when said intake manifold is at negativepressure conditions.
 3. In an internal-combustion engine, as set forthin claim 1, wherein said third means comprises a casing in surfacecontact with said intake manifold, the interior of said casing being incommunication with the atmosphere, a pipe line connecting said casing tosaid fuel line and said pipe line communicating with said fuel line at alocation downstream from the connection of said branch pipe to said fuelline, a bimetal member positioned within said casing, a valve mounted onsaid bimetal member and arranged to maintain the opening closed when theengine temperature is below a predetermined level and to displace thevalve from the opening when the engine temperature reaches apredetermined level for admitting air into said fuel line fordiscontinuing flow therethrough to said venturi tube.
 4. In aninternal-combustion engine, as set forth in claim 1, wherein said fuelwell has an outlet from its lower end connected to said conduit, saidvalve means arranged to open and close said outlet, said valve meanscomprises a valve member including a valve stem extending upwardly fromsaid valve member, a diaphragm extending across the upper end of saidfuel well and dividing it into a lower fuel containing part and an upperdiaphragm chamber, and said pressure means comprises a fuel tank, a pipeconnecting said fuel tank to said float chamber, a pump for supplyingfuel from said fuel tank to said fuel chamber, and a branch line fromsaid pipe connected to said diaphragm chamber downstream from said pumpso that the pressure in said pipe is supplied into said diaphragmchamber and when said pump is operating the pressure supplied into saiddiaphragm chamber depresses the valve downwardly into position forclosing the outlet from said fuel well.
 5. In an internal-combustionengine, as set forth in claim 1, wherein a water jacket is providedabout a portion of said manifold intake, said third means comprises atemperature sensor arranged to detect the water temperature within saidwater jacket, solenoid valve having an opening to the atmosphere, pipeline connecting said solenoid valve to said fuel line and said pipe linecommunicating with said fuel line at a location downstream from theconnection of said branch pipe to said fuel line, said solenoid valvearranged to control flow into said pipe line, and an electroniccontroller connected to said temperature sensor and said solenoid valveso that said temperature sensor signals said electronic controller whenthe temperature of the water in the water jacket reaches a predeterminedlevel and actuates said solenoid valve for admitting the flow ofatmospheric air into said pipe line.
 6. In an internal-combustionengine, as set forth in claim 1, wherein a fuel intake pipe extendsbetween said float chamber and said fuel well and an air pipe locatedabove said fuel intake pipe extends between said float chamber and saidfuel well, said fuel chamber having an opening in its lower end, saidconduit connecting said fuel well to said fuel chamber is connected tothe lower end of said fuel well and to the opening in the lower end ofsaid fuel chamber, a floatable check ball located within said fuelchamber for closing off the opening to said conduit into said fuelchamber when fuel is emptied from said fuel chamber, said fuel lineextending upwardly from said fuel chamber to its point of connection tosaid branch pipe and downwardly to said venturi tube, a first orificelocated in said fuel line at the opening from said fuel chamber, andsecond orifices located in said fuel line and in said branch pipeconnected to said fuel line for regulating flow of air and fueltherethrough.